When working with Kubernetes, one common challenge is how to reliably communicate with your pods. Pods are dynamic—they can be created, deleted, or restarted, which means their IP addresses keep changing. That’s where ClusterIP Services come in.
What is a ClusterIP Service?
- Internal load balancer for your cluster: It provides a stable internal IP or DNS name so other pods or services inside the cluster can reach it.
- Layer 4 load balancing: It operates at the TCP/UDP level to distribute traffic among your pods.
- DNS-based access: You don’t need to worry about individual pod IPs.
Why do we need it?
Pods have ephemeral IPs. If a pod dies and restarts, its IP changes. Without a stable address, other services won’t know where to send traffic. ClusterIP solves this problem by giving your pods a single, consistent internal IP and DNS name.
How it works
When you create a ClusterIP service, Kubernetes automatically:
- Assigns it a stable internal IP.
- Creates a DNS name that internal clients can use:
<service-name>.<namespace>.svc.cluster.local
For example:
my-clusterip-service.default.svc.cluster.local
Internal pods can now send requests to this DNS name instead of tracking individual pod IPs. Kubernetes will load-balance traffic to all healthy pods behind the service.
Key Takeaways
- ClusterIP is internal only (not accessible outside the cluster).
- Provides load balancing for pods.
- Ensures stable communication via DNS even when pods restart.
If you’re running multiple microservices in GKE, ClusterIP is your go-to solution for internal service communication.
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— Latchu | Senior DevOps & Cloud Engineer
☁️ AWS | GCP | ☸️ Kubernetes | 🔐 Security | ⚡ Automation
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